This invention relates to circuit components mounted on circuit boards by solder column arrays, and more particularly, to column grid arrays and a method of supporting them.
Solder column arrays are used to interconnect circuit packages to circuit boards, most typically large ceramic integrated circuit packages. One such package is the column grid array package (CGA) that has a ceramic substrate with an array of solder columns that extend out from it, typically from the bottom surface. The solder columns are attached at one end to connection pads or locations on the ceramic substrate. The solder columns are sufficiently tall so that when the circuit package is placed on a circuit board, the solder columns can accommodate the difference in thermal expansion between the ceramic integrated circuit package and the printed circuit board. The solder columns are soldered to respective pads on the circuit board using known techniques, such as a convection reflow solder process.
One problem with solder column arrays is that the solder columns do not withstand compressive force, vibration, or shock well. The solder columns in the solder column arrays are made of approximately ninety percent eutectic solder, which is a soft material. Moreover, the individual solder columns are very thin. Consequently, if any significant amount of compressive force, vibration or shock is applied to the circuit package the solder column array may compress or otherwise weaken or deteriorate, particularly over time, which may compromise reliability. Thus, it is desirable to provide a mechanism to reduce the force, shock or vibration which may impact the CGA integrated circuit.
In one aspect of the present invention, an apparatus for improved shock and vibration isolation of a circuit component utilizing solder column grid arrays to provide electrical connection to a base component is provided. The apparatus includes a support frame attached to the circuit component and to the base component which supports the circuit component on the base component. Also included is an isolation material located at a point between the circuit component and the base component such that a vibration or shock to the base component must travel through the isolation material prior to reaching the integrated circuit. The point where the isolation material is provided between the circuit component and the base component is preferably at least one of the points between the support frame and the circuit component, between the support frame and the base component, or between two components of the support frame.
In another aspect of the present invention, an apparatus for improved shock and vibration isolation of a CGA integrated package which utilizes solder column grid arrays to provide electrical connection to a circuit board and which includes a substrate and a package lid is provided. The apparatus includes a support frame attached at an attachment point to the substrate or the package lid of the integrated package and at a second attachment point to the circuit board. Also included is an isolation material located at the attachment point of the support frame to the substrate or the package lid, or located at the second attachment point of the support frame to the circuit board such that a vibration or shock to the circuit board must travel through the isolation material at the attachment point prior to reaching the integrated circuit.
In another aspect of the present invention, a method of supporting a circuit component on a base component and improving the isolation of the circuit component from any vibration and shock to the base component is provided. The method includes the step of providing a support frame which supports the circuit component and attaches the circuit component to the base component. Also included is the step of providing an isolation material at a point between the circuit component and the base component such that a shock or vibration to the base component must pass through the isolation material before reaching the circuit component.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.